1,286 research outputs found
Quantitative studies for photoabsorption and fluorescence of HCl
Photoabsorption and fluorescence cross sections of HCl are investigated in the wavelength region between 105 to 220 nm. The oscillator strengths of discrete structures at wavelengths shorter than 130 nm are measured
OH(A-X) fluorescence from photodissociative excitation of HO2 at 157.5 nm
The OH(A-X) fluorescence from photodissociative excitation of HO2 by F2 laser photons (157.5 nm) was observed and compared with the OH fluorescence spectra of H2O2 and the O2+CH3OH mixture. The rotational population distributions of OH(A) were obtained from the fluorescence spectra. The most populated levels are J = 4 for photodissociative excitation of HO2, J = 20 for H2O2, and J = 21 for the O2+CH3OH mixture. The fluorescence from the gas mixture is attributed to the O + H recombination for which the atoms are produced from photodissociation of parent molecules
Can Geometric Test Probe the Cosmic Equation of State ?
Feasibility of the geometric test as a probe of the cosmic equation of state
of the dark energy is discussed assuming the future 2dF QSO sample. We examine
sensitivity of the QSO two-point correlation functions, which are theoretically
computed incorporating the light-cone effect and the redshift distortions, as
well as the nonlinear effect, to a bias model whose evolution is
phenomenologically parameterized. It is shown that the correlation functions
are sensitive on a mean amplitude of the bias and not to the speed of the
redshift evolution. We will also demonstrate that an optimistic geometric test
could suffer from confusion that a signal from the cosmological model can be
confused with that from a stochastic character of the bias.Comment: 11 pages, including 3 figures, accepted for publication in ApJ
The Gravitational Lensing in Redshift-space Correlation Functions of Galaxies and Quasars
The gravitational lensing, as well as the velocity field and the cosmological
light-cone warp, changes the observed correlation function of high-redshift
objects. We present an analytical expression of 3D correlation function,
simultaneously including those three effects. When two objects are separated
over several hundreds Mpc along a line of sight, the observed correlation
function is dominated by the effect of gravitational lensing rather than the
intrinsic clustering. For a canonical lambda-CDM model, the lensing signals in
the galaxy-galaxy and galaxy-QSO correlations are beyond noise levels in
large-scale redshift surveys like the Sloan Digital Sky Survey.Comment: 10 pages, 1 figure, submitted to ApJ
Imaging Simulations of the Sunyaev-Zel'dovich Effect for ALMA
We present imaging simulations of the Sunyaev-Zel'dovich effect of galaxy
clusters for the Atacama Large Millimeter/submillimeter Array (ALMA) including
the Atacama Compact Array (ACA). In its most compact configuration at 90GHz,
ALMA will resolve the intracluster medium with an effective angular resolution
of 5 arcsec. It will provide a unique probe of shock fronts and relativistic
electrons produced during cluster mergers at high redshifts, that are hard to
spatially resolve by current and near-future X-ray detectors. Quality of image
reconstruction is poor with the 12m array alone but improved significantly by
adding ACA; expected sensitivity of the 12m array based on the thermal noise is
not valid for the Sunyaev-Zel'dovich effect mapping unless accompanied by an
ACA observation of at least equal duration. The observations above 100 GHz will
become excessively time-consuming owing to the narrower beam size and the
higher system temperature. On the other hand, significant improvement of the
observing efficiency is expected once Band 1 is implemented in the future.Comment: 16 pages, 12 figures. Accepted for publication in PASJ. Note added in
proof is include
The Rossiter-McLaughlin effect and analytic radial velocity curves for transiting extrasolar planetary systems
A transiting extrasolar planet sequentially blocks off the light coming from
the different parts of the disk of the host star in a time dependent manner.
Due to the spin of the star, this produces an asymmetric distortion in the line
profiles of the stellar spectrum, leading to an apparent anomaly of the radial
velocity curves, known as the Rossiter - McLaughlin effect. Here, we derive
approximate but accurate analytic formulae for the anomaly of radial velocity
curves taking account of the stellar limb darkening. The formulae are
particularly useful in extracting information of the projected angle between
the planetary orbit axis and the stellar spin axis, \lambda, and the projected
stellar spin velocity, V sin I_s. We create mock samples for the radial curves
for the transiting extrasolar system HD209458, and demonstrate that constraints
on the spin parameters (V sin I_s, \lambda) may be significantly improved by
combining our analytic template formulae and the precision velocity curves from
high-resolution spectroscopic observations with 8-10 m class telescopes. Thus
future observational exploration of transiting systems using the Rossiter -
McLaughlin effect is one of the most important probes to better understanding
of the origin of extrasolar planetary systems, especially the origin of their
angular momentum.Comment: 39 pages, 16 figures, Accepted to ApJ. To match the published version
(ApJ 623, April 10 issue
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